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NIHR Signal New airway device as good as tracheal tube insertion for out-of-hospital resuscitation

A supraglottic airway device works as well as a tracheal tube for paramedics resuscitating patients in cardiac arrest and is simpler to use.

People who have stopped breathing need to get air into their lungs urgently. Usually, a tube is placed through the vocal cords into their trachea to secure a reliable airway, but correct placement needs skill and practice and can interrupt chest compressions during resuscitation. More recently, paramedics have used a supraglottic airway device, placed in the throat above the vocal cords, which is quicker to insert and requires less training for reliable placement. Few studies have compared the two interventions.

This study of 9,296 patients found no important difference in the proportion who survived between those who were randomly assigned to intubation (8.5%) and those assigned to the airways device (8.1%). The findings suggest that either can be used, according to the circumstances and the training of the paramedic.

Why was this study needed?

Cardiac arrest out of hospital is usually fatal. In 2014, emergency medical services in England attempted resuscitation of almost 30,000 people, around 8% of whom survived. The best way to keep an airway to the lungs when patients’ breathing had stopped was uncertain.

Options include basic mouth-to-mouth breathing or bag-and-mask techniques. Tracheal intubation has been seen as the standard of care for advanced breathing assistance. However, it can only be done by paramedics with training who have the opportunity to maintain their skills.

The supraglottic airway device (SGA) introduced an option which more paramedics were able to use, but there was little evidence to show whether it works as well as intubation.

This study aimed to find out whether one device was more likely to lead to a good outcome than the other.

What did this study do?

The AIRWAYS-2 trial randomised 1,523 paramedics to prioritise either intubation or use of SGA when they were called to an eligible patient. They enrolled 9,296 patients when they were the first or second paramedic on the scene. Eligible patients were adults with a non-traumatic out of hospital cardiac arrest, which required advanced airways management (beyond mask and bag breathing assistance).

Paramedics were requested to make two attempts at their allocated technique before switching to the alternative option. They were able to use the non-allocated option if their clinical judgement suggested it would be preferable. Enrolled patients were followed up for 30 days, or until death or hospital discharge.

Though paramedics were given training on their allocated technique, individual expertise may have influenced the results.

What did it find?

In the SGA group, 311 patients (6.4%) had a good outcome after 30 days, compared with 300 patients (6.8%) in the intubation group. This was measured by scoring 0 to 3 on the modified Rankin Scale of neurological disability, where 0 represents no symptoms and 3 represents moderate disability but able to walk without assistance. The adjusted risk difference of -0.6% was not significant (95% confidence interval [CI] -1.6 to 0.4).

There was little difference in the number of patients who had died by 30 days - 91.9% of the SGA group compared to 91.5% of the intubation group.

The initial attempts at ventilation were more often successful when paramedics used SGA (87.4%) than when they used intubation (79.0%), with an increased chance of initial success for paramedics using SGA, adjusted risk difference 8.3% (95% CI 6.3 to 10.2).

There was no significant difference in the potential complications of regurgitation (bringing up stomach contents) or aspiration (inhaling stomach contents) between the two procedures. Regurgitation occurred with 24.5% of attempts at intubation and 26.1% of attempts at SGA placement. Aspiration occurred with 14.9% of attempts at intubation and 15.1% of attempts at SGA placement.

What does current guidance say on this issue?

The 2015 Resuscitation Council guidelines say that clinicians should use the airway technique with which they are most experienced to provide adequate oxygenation and ventilation. The optimal airway technique for cardiac arrest is unknown and is likely to depend on the skills of the operator, the anticipated pre-hospital time and patient-dependent factors.

A 2018 consensus statement on intubation from the College of Paramedics says that intubation should remain part of the training and skill set of paramedics, but points to a lack of nationally agreed standards on education and training. It says it will develop guidelines to address this.

What are the implications?

Widespread adoption and use of SGA has reduced the numbers of tracheal intubations carried out by paramedics in emergencies. The results of this study should provide reassurance that this does not represent a lesser standard of care, and that patients treated with SGA are no less likely to have a good outcome than those treated with intubation.

It is likely that these results will inform future guidance and training in advanced airways management for paramedics.

Expert commentary

Benger et al. report the outcome of the much anticipated AIRWAYS2 trial in the Journal of the American Medical Association. They compared the use of a supraglottic airway device to tracheal intubation as the initial advanced airway management strategy following non traumatic out-of-hospital cardiac arrest.

This well designed study demonstrated no difference in primary outcome (modified Rankin Score 0-3) between the two groups based on intention to treat analysis. Interestingly the supraglottic airway was associated with higher success rates compared to tracheal intubation. Intubation was associated with less regurgitation. However, these secondary outcomes were exploratory and not powered to show a difference.

Expert commentary

Using a supraglottic airway device provides no patient outcome advantage over tracheal intubation in management of out of hospital cardiac arrest. How does this help clinical practice?

In the full text of the paper, the excellent Figure 2 is worth close scrutiny as it provides a fascinating map of the complex clinical decisions that are made about the choice of intervention and when to use them as are the subgroup analyses that balance benefits against potential complications.

Clinical decision making is rarely black or white, and the findings provide new evidence that can refine what is ultimately the most important interaction between patient and clinician.

Janette Turner, Reader in Emergency and Urgent Care Research, University of Sheffield

The commentator declares no conflicting interests

Definitions

The modified Rankin Scale of neurological disability is a 6-point scale ranging from 0 (no symptoms) to 6 (dead). A score of 0 to 3 was considered a good outcome in this study.